The question is not clear about asking for upvote in the comments of other or in one own post.
If someone is adding request for upvote at the end of his/her own post it seems to be logical.
But asking for upvote in the comments of other people post doesn't attract any upvote rather in most of the time it offends the users.
I think instead of asking for upvotes one should try to focus on good quality of post so that anyone reading it should be attracted towards it to upvote.
